RaspberryPi Temperature Sensor
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Time to build a temperature sensor with my Pi.
Schematics
Configure the Pi
Update the OS
This not necessary, but generally a good idea.
apt-get update apt-get ugrade
Install missing packages
If you have already installed them, you can skip this step.
apt-get install bc apt-get install gnuplot
Setup kernel modules for GPIO and 1-wire device
modprobe w1-gpio modprobe w1-therm
Check setup
Check whether there is now our sensor device:
cd /sys/bus/w1/devices ls -1
10-000802ad5087[1] w1_bus_master1
See it's content (values):
cd 10-000802ad5087[2] cat w1_slave
39 00 4b 46 ff ff 03 10 9c : crc=9c YES 39 00 4b 46 ff ff 03 10 9c t=28562[3]
Code
This is how I read the device and generate a nice plot using GNUplot:
#!/bin/bash #set -x # # Script: readTemperature.sh # Author: Heiko Kretschmer # Purpose: Reading the temperature and generating a nice plot # # # # Globals # GDEVICEID="10-000802ad5087" GDEVICESPATH="/sys/bus/w1/devices" GDEVICEVALUEFILE="w1_slave" GTIMESTAMPFORMAT="%Y-%m-%d_%H:%M" GTIMESTAMP="`date +${GTIMESTAMPFORMAT}`" GTIMESTAMPTIME="`date '+%H:%M'`" GTIMESTAMPDATE="`date '+%Y-%m-%d'`" # ISO 8601 date format GTIMESTAMPDATEHUMANREADABLE="`date '+%A, %Y-%m-%d'`" GFOLDERBASE="/home/pi/Development/temperature" GFOLDERLOGS="${GFOLDERBASE}/logs" GFOLDERGRAPHS="${GFOLDERBASE}/graphs" GFOLDERTMP="${GFOLDERBASE}/tmp" GFILELOG="${GFOLDERLOGS}/readTemperature_${GTIMESTAMPDATE}.log" GFILEGRAPH="${GFOLDERGRAPHS}/readTemperature_${GTIMESTAMPDATE}.svg" GFILEPLOTCOMMANDS="${GFOLDERTMP}/readTemperature-plot.cmd" # # Main # # Init test ! -d "${GFOLDERLOGS}" && mkdir "${GFOLDERLOGS}" test ! -d "${GFOLDERGRAPHS}" && mkdir "${GFOLDERGRAPHS}" test ! -d "${GFOLDERTMP}" && mkdir "${GFOLDERTMP}" # Get the temperature VALUERAW="`cat \"${GDEVICESPATH}/${GDEVICEID}/${GDEVICEVALUEFILE}\" | grep t= | cut -d= -f2`" VALUE="`echo \"scale = 3; ${VALUERAW} / 1000\" | bc`" #echo Temperature: ${VALUE} # Write it into the log (one logfile per day to get nice graphs) echo -e "${GTIMESTAMPTIME}\t${VALUE}" >> "${GFILELOG}" # Generate the graph test -f "${GFILEPLOTCOMMANDS}" && rm "${GFILEPLOTCOMMANDS}" echo "set key inside right top vertical Right noreverse enhanced autotitles columnhead nobox" >> "${GFILEPLOTCOMMANDS}" echo "set timefmt \"%H:%M\"" >> "${GFILEPLOTCOMMANDS}" echo "set xdata time" >> "${GFILEPLOTCOMMANDS}" echo "set format x \"%H:%M\"" >> "${GFILEPLOTCOMMANDS}" echo "set style data linespoints" >> "${GFILEPLOTCOMMANDS}" echo "set xtics \"01:00\" rotate by 90 offset 0,-2 out" >> "${GFILEPLOTCOMMANDS}" echo "set title \"Temperature on day ${GTIMESTAMPDATEHUMANREADABLE}\"" >> "${GFILEPLOTCOMMANDS}" echo "set ylabel \"°C\"" >> "${GFILEPLOTCOMMANDS}" echo "set xlabel \"Time\"" >> "${GFILEPLOTCOMMANDS}" echo "set yrange [ 0.000 : ] noreverse nowriteback" >> "${GFILEPLOTCOMMANDS}" echo "set term svg" >> "${GFILEPLOTCOMMANDS}" echo "set output \"${GFILEGRAPH}\"" >> "${GFILEPLOTCOMMANDS}" echo "plot \"${GFILELOG}\" using 1:2 title 'Temperature'" >> "${GFILEPLOTCOMMANDS}" cat "${GFILEPLOTCOMMANDS}" | gnuplot
You might want to use a cronjob like this:
*/15 * * * * /home/pi/Development/temperature/readTemperature.sh > /dev/null 2&>1
- Links
- Where I got the ideas from: http://www.raspberrypi-spy.co.uk/2013/03/raspberry-pi-1-wire-digital-thermometer-sensor/
- Where I learned to use xticks: http://psy.swansea.ac.uk/staff/carter/gnuplot/gnuplot_time.htm
- Nice to know: How to setup timezones: dpkg-reconfigure tzdata
- About various methods of connecting 1-wire devices: http://www.fhemwiki.de/wiki/Raspberry_Pi_und_1-Wire and http://blog.gegg.us/2013/03/4-different-methods-of-1-wire-access-on-raspberry-pi/
- More about Raspberry Pi on this website
- Footnotes: